Patch from Richard Sandiford <rsandifo@redhat.com>

	* reload1.c (choose_reload_regs): Prevent the find_equiv_reg() code
	from inheriting a subreg equivalence with a non-spill register.

	* tree.h (DECL_FUNCTION_CODE): Document that it is overloaded.

From-SVN: r94529

gcc/ChangeLog

+2005-02-01  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	Patch from Richard Sandiford <rsandifo@redhat.com>
+	* reload1.c (choose_reload_regs): Prevent the find_equiv_reg() code
+	from inheriting a subreg equivalence with a non-spill register.
+
+	* tree.h (DECL_FUNCTION_CODE): Document that it is overloaded.
+
 2005-02-01  Alexandre Oliva  <aoliva@redhat.com>
 
 	* config/frv/frv.c (movcc_fp_destination_operand): New.

gcc/reload1.c

@@ -5589,6 +5589,15 @@ choose_reload_regs (struct insn_chain *chain)
 		      gcc_assert (GET_CODE (equiv) == SUBREG);
 		      regno = subreg_regno (equiv);
 		      equiv = gen_rtx_REG (rld[r].mode, regno);
+		      /* If we choose EQUIV as the reload register, but the
+			 loop below decides to cancel the inheritance, we'll
+			 end up reloading EQUIV in rld[r].mode, not the mode
+			 it had originally.  That isn't safe when EQUIV isn't
+			 available as a spill register since its value might
+			 still be live at this point.  */
+		      for (i = regno; i < regno + (int) rld[r].nregs; i++)
+			if (TEST_HARD_REG_BIT (reload_reg_unavailable, i))
+			  equiv = 0;
 		    }
 		}
 

gcc/tree.h

@@ -2000,8 +2000,10 @@ struct tree_binfo GTY (())
    that describes the status of this function.  */
 #define DECL_STRUCT_FUNCTION(NODE) (FUNCTION_DECL_CHECK (NODE)->decl.u2.f)
 
-/* For FUNCTION_DECL, if it is built-in,
-   this identifies which built-in operation it is.  */
+/* For FUNCTION_DECL, if it is built-in, this identifies which built-in
+   operation it is.  Note, however, that this field is overloaded, with
+   DECL_BUILT_IN_CLASS as the discriminant, so the latter must always be
+   checked before any access to the former.  */
 #define DECL_FUNCTION_CODE(NODE) (FUNCTION_DECL_CHECK (NODE)->decl.u1.f)
 
 /* The DECL_VINDEX is used for FUNCTION_DECLS in two different ways.